This invention relates to a novel liquid flame retardant having a high bisphenol-A bis(diphenyl phosphate) content.
Bisphenol-A bis(diphenyl phosphate) is a well known flame retardant for use in normally flammable resins and is especially useful in flame retarding polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) compositions. It also finds use as a flame retardant in polyphenylene oxide/styrene compositions.
The art is replete with processes and process improvements for the production of bisphenol-A bis(diphenyl phosphate). See, for example, U.S. Pat. No. 2,520,090; U.S. Pat. No. 5,281,741; U.S. Pat. No. 5,750,756; GB 734,767; and WO 98/35970.
Despite past efforts, there is still a need for a liquid bisphenol-A bis(diphenyl phosphate)-based flame retardant which is resistant to crystallization at room temperature but which has a high phosphate content and a very low impurity content. It is an object of this invention to address such need. It is also an object of this invention to provide an improved bisphenol-A bis(diphenyl phosphate)-based flame retardant. It is a further object of this invention to provide a resin formulation containing the bisphenol-A bis(diphenyl diphosphate)s of the invention.